The present disclosure relates to a composition for an etching process, and more particularly, to a high-selectivity etching composition capable of selectively removing a nitride layer while minimizing an etch rate of an oxide layer and to a method for fabricating a semiconductor using the etching composition.
In manufacturing semiconductors, an oxide layer and a nitride layer have been used as an insulating layer. The oxide layer may include a silicon oxide (SiO2) layer, and the nitride layer may include a silicon nitride (SiN2) layer. The silicon oxide layer and the silicon nitride (SiN2) layer are used independently or alternatively stacked with each other as the insulating layer. Furthermore, the oxide layer and the nitride layer may be used as a hard mask for forming a conductive pattern for metal interconnections.
A wet etching process may be carried out for removing such a nitride layer. Typically, as an etching composition, a mixture of a phosphoric acid and deionized water is used for removing the nitride layer. The deionized water may be added to prevent deterioration of an etching rate and variation of etching selectivity. However, even small variation in a supplied amount of the deionized water might cause defects in the etching process for removing the nitride layer. Furthermore, it is very difficult to handle the phosphoric acid because the phosphoric acid has strong acid property and has corrosiveness or causticity.
In order to overcome such defect of the typical etching composition, etching composition including phosphoric acid (H3PO4) mixed with one of hydrofluoric acid (HF) and nitric acid (HNO3) was introduced. However, such etching composition deteriorates the etching selectivity of a nitride layer and an oxide layer. Another etching composition including a phosphoric acid and one of a silicate and a silicic acid was introduced. However, the silicate and the silicic acid cause generating particles that badly influence a substrate.